


Empty

by TechnoBeat



Category: Undertale (Video Game)
Genre: Angst, Grillster, Implied/Referenced Rape/Non-con, M/M, Sanster, Wartime Sanster AU, kingdings
Language: English
Status: Completed
Published: 2021-02-09
Updated: 2021-02-17
Packaged: 2021-03-15 02:08:33
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 4
Words: 2,615
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29306253
Author URL: https://archiveofourown.org/users/TechnoBeat/pseuds/TechnoBeat
Summary: Wartime au angst, that's pretty much it. Inspired by hyliank8's wartime sanster au (or at least the first chapter is. Other than that it will differ a lot from headcanons, I think.)
Relationships: Asgore Dreemurr/W. D. Gaster, W. D. Gaster & Grillby, W. D. Gaster/Sans
Comments: 11
Kudos: 13





	1. Light of my life, lost

It had to be somewhere around here. Asgore said there should be a few vials of DT left in the medical tent. Gaster glanced behind him to see how Sans was holding up, and it didn't look good. The skeleton had lost his right eye thanks to a shot from a human mage, and with it had come a gaping hole through his head.

* * *

_Gaster had rushed to the front lines to get Sans out of there, but as soon as he got to the front he had noticed he was too late. Soldiers were running towards him as he had rushed to the beaten up skeleton, who was so near to dusting away with the gentlest of breezes._

* * *

Nothing in this drawer either. Despair was starting to get the better of him as his appendage hands flew around the medical tent, making more of a mess rather than helping. Few of them were gently holding Sans' hand and face, as if in an attempt to heal him with affection alone.

It didn't do anything of course.

* * *

_When he picked up the small frail body, panic tried to take hold of him, but he had to stay calm, for his sake. Gaster came to the conclusion that in his current state of mind, he'd need help, so that he wouldn't do anything stupid._

_Asgore could surely help._

* * *

One of the appendages found a syringe, but it was empty, same as the few vials he had managed to find laying around. Asgore had said there would be some here, so where are they?

A monster from the medical staff enters the tent.

"Doctor Gaster? What are you doing here? Shouldn't you be at the main base?"

"Oh, thank the stars, help me out here, I need to find DT extract to-"

"Why are you looking for DT extract? We ran out of it yesterday and are waiting for the next delivery from the main base, so why aren't you there helping with the production?"

Gaster stops and looks at the monster with hollow eyes, as dread fills his insides.

"...Ran out? RAN OUT?! OF THE ONE THING KEEPING US ALIVE AGAINST THE HUMANS? MY ONLY HOPE FOR SAVING HIM!?" 

The other monster looks to where Gaster's hand is pointing, and sees the nearly dusted skeleton.

"No, No, NO!" Gaster rushes next to Sans, and sees that everything below his ribcage had already dusted. "No- Sans, please wake up, you can't let everything end like this!"

There is no response whatsoever. Not a single sound to indicate that he is reacting on any level. It's as if he was already gone, but that couldn't be it, there had to still be a chance to make things right. He was still here, he had to be.

The other monster looks at the Doctor, who is now in a shock, just gently petting what was left of the skeleton's body. But he wasn't crying, no, he was staring the skeleton's empty eye socket, seemingly waiting for a sign.

Anything.

But nothing happened.

"Please," Gaster said as he watched Sans' shirt go flat as one rib after another disappears to thin air, "Don't leave me like this."

The sound of a shattering soul fills his mind, as a relentless river of tears starts to fall along his cheeks, accompanied by a blood freezing screech.

The medical staff monster backed slowly towards the exit of the tent and then started running as fast as they could. The chilling echo of the wailing would stay with them for a long time.


	2. And you took him from me

**Summary for the Chapter:**

> After the incident at the medical tent, Gaster wants some answers.

He stormed through the barracks of the main base towards the king.

He wanted answers.

"Asgore," Gaster said, his fists shaking as he tried to control himself, "I need a word with you, right now."

The king looked at him confused. "My dear friend, you know that I cannot leave my position as of now, and I really do not have the time no matter how much I wish to hear what you have to say."

"It wasn't a request, my king." The words were filled with malice and spite. Asgore looked at the trembling doctor, and nodded slightly.

"Hmm, fine, it seems that this matter needs to be dealt with now."

The two of them retreat to the king's tent, and as soon as Asgore closes the entrance, Gaster lashes out at him.

"Why didn't you tell me we had run out of DT extract!? You made me go to the other side of the battlefield, running in circles! I watched the one I hold dear dust before my eyes!"

Tears were now freely falling down on Gaster's face, but Asgore just shrugged.

"That is, unfortunately, how life goes during a war dear friend."

He walked towards the doctor and continued, "This... friend of yours, just wasn't cut out for this kind of thing. You did your best, and I'm here to help you get over it the best I can."

He lifted Gaster's trembling face to meet his eyes, but Gaster smacked his hand away.

"Get over this!? GET OVER, THIS!? How could I!? If I hadn't been withhold crucial information on our DT supply, there wouldn't be anything to get over of!"

Asgore looked a bit insulted. "Withold information? Are you actually accusing me for your friends dusting? Dear stars, grieve has made you irrational friend."

Gaster stared down on the king with venom in his eyes, "Yes, yes I am _friend._ There is simply no way you hadn't known that the medical unit needed a new supply, and yet you sent me to that tent, knowing full well I wouldn't find anything there."

He was trying to hold himself together, fearing that if he didn't, he would try to kill the king before getting any answers.

The king stroked his beard, and the silence was deafening until he finally started to speak.

"Nothing escapes your calculating mind, does it my dear?" He took a few steps closer, and Gaster could feel dread taking hold of himself yet again. "Fine then, I did know of the shortage, but I had my reasons for deceiving you in this way."

"What could possibly be a good enough excuse for-"

A hand slams him to the king's desk and knocks the breath out of him, as Asgore continues.

"The excuse would be that this _friend_ was holding you back," he proceeds to caress Gaster's face gently, "I couldn't just stand there and watch you waste yourself with an inferior monster like _him_."

"You- I _trusted_ you! You were my oldest friend, how could you do this to me, to him!?"

Asgore put his finger on Gaster's lips.

"It's because I love you, and cannot stand the thought of you ruining your life. I did it so that nothing would stand between us, my dear friend."

Gaster felt a piece of his soul crack away as the king embraced and kissed him deeply.


	3. Unwilling to let go

**Summary for the Chapter:**

> The war was lost, and the monsters now lived Underground.  
> Gaster has regular nightmares of losing his love, and life is difficult.

He woke up to his own screams yet again. Gasping for air he tried to calm himself down, saying that it was okay, he was fine. It was just the same nightmare he'd seen since the incident.

Gaster was still shaking a bit when he got up. There was no way he could sleep tonight anymore, that was certain. He went to grab his jacket and went for a night walk.

* * *

Grillby is cleaning the counter, ready to close for the night, when the door opens and Gaster walks in, stumbling a bit.

"Hey Grillby, I- I know it's late, but could you get me cup of the usual?"

The doctor looks shaken up, like he often does when he comes by this late. Grillby knows of his friends nightmare, and nods, gesturing him to sit down at the counter.

Seemingly relaxing a bit, Gaster takes a seat and thanks the bartender. Grillby hands the doctor a cup of tea, a special blend he'd made.

Gaster drinks a few sips, and takes a shaky breath.

"Was it the same nightmare again?" Grillby asks, and waits for him to reply.

Gaster sighs, sounding defeated. "Yes... this always happens whenever I've had to meet with _him_."

His hands begin shaking mentioning _him_ , and Grillby places his hand over Gaster's, running his thumbs gently over the backs of the doctors hands.

"I wish I could do more to help." Grillby says, and lifts the other hand to his mouth, and gives it a gentle kiss. "I hate to see you suffer like this."

Blushing lighly, Gaster pulls away his hands and finishes his drink, while the two of them stay in silence.

Then Grillby speaks up.

"You know that if you could always come live here, right? My door is always open for you."

The doctor looks surprised.

"What's this about all of a sudden?" Gaster says, knowing full well what this was about. Grillby had offered to house him for years now. 

It had begun after an especially horrid meeting with the king. That day he confided in the bartender, he had told to him everything from the beginning, of the nightmares, and about what the king truly did each and every meeting with him...

Gaster looks into Grillby's eyes with what looks like regret and sorrow. He wanted to love this monster so badly, but he hadn't been able to move on. He just couldn't, not before he could somehow pay back for all the king had done.

And Grillby knew this.  


Noticing the storm of memories gathering inside his friends head, Grillby tells Gaster to try and forget he mentioned it.

Then Grillby takes Gaster's hands into his, and looks straight at him with a small, gentle and sincere smile.

"I'm sorry, I know we've talked about this before, and I know your reasons, but still, I will be here for you whenever you need me."

Gaster sighs. "I know, I know, and... thank you. I'm- I'm not sure I could take this any longer if it wasn't for you."

They are both blushing slightly, and Grillby inches towards the doctor.

"Gaster, I-"

He's interrupted as Gaster pulls his hands away swiftly.

"It's- it's really late, I need to get going, thank you for tonight Grillby." 

He gets up and walks out the door, leaving Grillby behind. The bartender feels his soul ache, as the door closes.


	4. I can't wait to see you again

**Summary for the Chapter:**

> After a few months since Gaster's last visit, Grillby hears and unsettling rumor from one of the customers.

It had been months since Gaster's visit, and Grillby was getting more anxious by the day. He wanted to give the doctor the space he needed, but he's never had to wait for him this long. 

_Had Asgore done something to him?..._

Grillby shook his head, trying to get the thought out. Gaster had told him how dependent the king had become of him, there should be no reason for anything worse than what has been going on to happen.

"Hey, did you hear the rumors yeah?" said a monster to another sitting next to them at the counter, "the royal scientist, that he's fallen down?"

A glass falls to the ground, shattering to a thousand pieces, and the monsters in the bar turn to look at Grillby.

Then Grillby asks the monster where they had heard the rumor.

"Why do you care?" The monster asks with a nonchalant smirk, "is he your boyfriend or something?"

Grillby felt a sting in his soul. 

He stood there, shaking, until he bolted towards the exit, accompanied by the confused and worried questions by the monsters in the bar.

"Woah, Grillby, you alright bud? Where you going?"

Halting for a moment, Grillby announces that the bar was closed for the day, and told everyone to leave. He stayed at the door until every displeased monster had left the bar, and then started running.

He had to see Gaster.

* * *

Huffing and barely standing up, Grillby knocks at Gaster's door. When he'd asked at the labs where the doctor was, they had told him he was at the medical wing, and which door he'd need to go to. Dread had taken hold of him, and he had run here without letting the staff member finish their sentence.

It felt like he had waited an eternity before the door opened.

"Wha-? Grillby, what are you doing here?"

Gaster stood there confused, as Grillby hugged him. A weight was lifted off of his soul, as he held him close. He was alive, it had been nothing but a rumor after all.

A few staff members had gathered nearby, and whispers filled the air.

Gaster cleared his throat, and gently pushed Grillby until he let go of him.

"As I already asked, what are you doing here?" Gaster was visibly struggling to understand why the bartender had come here.

Suddenly realizing how odd it indeed was for him to have suddenly come here, when they'd last seen months ago, Grillby felt his face grow brighter.

"Someone at the bar said that you had fallen down and-"

Gaster's eyes grew wide, "Sorry to interrupt, but I think we should talk about this inside." He gestured Grillby to come in, and closed the door behind them.

As Gaster locked the door, Grillby saw how the doctor was hunched slightly, like he didn't have the strength to stand up straight.

Worry started to grow again in his soul.

He walked next to Gaster, and noticed that the doctor's breathing was shaky and shallow.

"Gaster, you know that I'm not the type to pry, but something is clearly wrong, and I'm really worried now. What happened? Did, did he-?"

Gaster cut him off by lifting his hand. He was visibly struggling to stand up and he was shaking fervently. Before Gaster could say anything, Grillby picked him up and carried him to the couch on the side of the room. He was much lighter than Grillby had even realized.

"You didn't have to do that, but thank you." Gaster said, steadying his breath.

Both stay quiet for a moment, before Gaster starts to talk.

"I- the rumor, it, it's partially true. I am very close to falling."

Grillby stays quiet, listening closely as his soul churned, and the doctor continues to describe the situation with his usual calm demeanor.

"One of my colleagues found me collapsed at the lab few months ago, and I didn't wake up until few days ago. My upper HP has diminished drastically, and it has shown no signs of stopping. The medicine we have has managed to slow it down a little, but I doubt I have much longer left."

Grillby can't believe what he's hearing, there is no way Gaster could just- there had to be a way to save him, and that's what Grillby said to Gaster. But the doctor just shook his head.

"There isn't a cure for this, and... I don't think I'd even want it." The last part was but a whisper, but to Grillby it was as loud as a cave crashing down.

"That's not funny doctor, why wouldn't you want to live!?" Grillby asks, clearly agitated by Gaster's disregard for his own life. "There is no way that the Gaster I know would give up without a fight!"

The doctor looks at the ceiling with hollow eyes.

"You know, I saw him when I was asleep. The birds were singing, the flowers were blooming... on those days, we would lay on the grass for hours, watching the clouds drift by in the gentle breeze..."

There is strong longing in the doctor's voice.

"Oh I miss him so, so much. I can't wait to see him again."

When he says that, Grillby sees that he is smiling. A cold shiver runs through his very being.

There is no light in the doctor's eyes.

**Author's Note:**

> I might continue or change this later on.


End file.
